Hey everyone! So I've been spending some time looking around the sight trying to find out what people think is the best engine and kit combinations and I've got a couple ideas but I'm not sold yet. I guess what I'm trying to do is get to a 40+mph bike with the least amount of money possible (I don't want to spend so much that I could have bought a used moped) while still maintaining reliability.

I weigh in at 175lbs.
The bike will be a full suspension mongoose MB that I plan on putting some high pressure cruising tires on.
We don't have any hills that I really need to worry about since I'm in Florida.
And I don't mind doing a little pedaling if I have to to get started.

What do you guys think, is it even feasible? Or am I just dreaming here and would need some serious cash for a high performance engine.

Interesting, what is illegal about it? I'll do some searching to see what a B&S engine is.

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Easier still, tie a rope to a friends car and tie the other end to your bike and have them drag you to 40+ mph to see if you got the nerve to go that fast on a bike in the first place, it worked for me! Happy Trails Walter F.

Great replies everyone! Duh, Briggs and Straton, I feel like a retard now..

Walter: what kind of rope should I use for this? ...jk
Pablo: The only thing about those china engines that I'm worried about is dependability. I'm not sure I want to go that route.

Perhaps I am being a bit too over zealous and 40mph is just a bit too fast. The thing is that I am trying to replace my car as effectively as possible and if I can't get half decent speeds it seems like I wont be able to utilize the bike as much as I'd like.

What kind of speeds do you guys think I can achieve with one of Dax's 4 stroke titan kits? What do you guys think about that engine and would I be better off with a titan/different kit or a different engine/Dax kit?

Hi
Remember it is a bicycle, designed for bicycle speeds
For reliable to and from work commuting I am using a 48 cc china girl (I am 220 lbs)
Mountain bike using cruise tires, front disk brake
Exhaust mod, tuned pipe alike, 36t rear sprocket
Just over a month w/o technical problems
It is more fun to cruise at low revs with no engine vibration
Peace
PD Hope to make the dual cable handle mod today

Pablo: The only thing about those china engines that I'm worried about is dependability. I'm not sure I want to go that route.

What kind of speeds do you guys think I can achieve with one of Dax's 4 stroke titan kits? What do you guys think about that engine and would I be better off with a titan/different kit or a different engine/Dax kit?

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Dependability is fine after you put a little bit into them. I've never been stranded. I think the simple little engines can be a lot more dependable than reputation!

DAX is good stuff from what I have seen, but I have no idea about speed with those.

Hi, I think the china engines are reliable and fast with a few changes. I am on my fifth one and have never had one to just die on me. I'm running 38mph with one. I have an expansion chamber and that is really the only thing I have added performance wise. I hope to reach 40mph also.

I would like to build a 6.5 hp push trailer capable of strong acceleration and 40 mph potential, just for kicks. However, with all my motored bikes, I like 20-25mph cruising speed. The roads I travel are too short, congested and filled with potholes to sustain higher speeds.

I'll have to agree with the folks who like a nice cruising speed of 20-25 MPH. I will probably always be fiddling with these because it's so much fun, but a bicycle just isn't built (yet) to go a sustained speed of 40 MPH comfortably and safely.

A real easy mod is to drill small holes in the plastic air filter cap. I also port & polish, (it's actually, a real easy Dremmel job, just don't get too enthusiastic with it!)

Wow, I didn't realize that people were still posting to this thread..don't know why I wasn't getting notifications. Thanks a ton for all the replies! Christmas is coming soon so I'm going to really have to figure out what I want to do.

I think that 40 is a little too fast for most bikes. I have hit 42 mph once on my Comfort bike. I did this riding no hands !!! Just kidding. I actually had a death grip on the bars. I have been to 60 plus mph on my Mazi Road bike. It felt good. But again. this is a very nice very expensive road bike. It will do 60mph and more down a good hill. It is a fast great handling road bike and built for speed , curves, and will stop on a dime. Only weighs around 18-19 lbs. But.. I would never put a motor on my road bike for lots of reasons. 99.9 percent of us put our little motors on Mountain bikes, Comfort bikes, and Cruisers. Bikes such as these could get you hurt real bad if not killed when going 40+ miles per hour. Once you get above 30mph on one of these style bikes, you are taking a real risk. They just were not made for speed. There are some full suspension bikes that you could safely go 40-50 mph. These bikes run huge 29 inch tires and cost 3000-4000 dollars. My point being.. If you want to cruise 40mph, you are asking too much out of most of the affordable bikes out there. And.. If the cops catch you going that fast, you could be arrested I would think. Next time you are going 30-35 mph, stick your head out of the window of your car. You will see that 30mph or so is really fast. Faster than you would want to fall anyway. If you want to run a Walmart Mongoose 40 mph or so, then you have a death wish for sure. A mongoose? Yikes !!! Don't do it !!! That way you can.. Enjoy the ride...

Look at a robin/subaru 1.6 hp 4 stroke. Staton has a great set up. You can buy their kit. I have 1 on my long wheel base recumbent. With the right gearing 35 wide open is possible. I would tone down your desire for 40 mph. 30 cruising on a bicycle is plenty fast.

Hmmmm....A low priced / high speed setup?......I'd try a "80 cc" HT , 27T rear sprocket (I've sold quite a few to FL people like yourself), and possibly a Power Pipe.....

I am running a 36T in hilly VA and can reach 34.4 MPH but I am at 6400 RPM (not good for sustained running in my opinion)....So the smaller sprocket should help immensely with RPM's....

You should be able to get 40 MPH with that setup...

Good Luck and please be safe!

Andrew

PS - Let us know what you end up with and how it did
- A shifter kit would be good too BUT you said you wanted to try to do
it on a budget.
- of course other mods like shaving the head etc... could be done too